1. Field of the Invention
The present invention relates to a resist removing agent, a composition for removing resist, a method for preparing the same and a resist removing method using the same. In particular, the present invention relates to use of an alkoxy N-hydroxyalkyl alkanamide as a resist removing agent, a composition for removing resist, a method for preparing the same, and a resist removing method using the same.
2. Description of the Related Art
The resist removing process is a major process in preparing a semiconductor device. After various processes for preparing a semiconductor device, e.g., an etching process (dry or wet) or an ion implantation process, a resist pattern used as a mask must be removed. Also, in the case when the resist pattern is misaligned, it must be removed to form a new resist pattern. In particular, various different material layers, e.g., an oxide layer, an aluminum layer, a copper layer, a polysilicon layer, a silicide layer or a polyimide layer, may be present under a resist layer to be removed. Therefore, an important consideration for a resist removing process is to remove a resist completely, as quickly as possible, and without attacking underlying layers.
A resist removing agent currently in wide use includes a basic amine such as hydroxyamine, diglycolamine, monoethanolamine or methylethanolamine, and a polar solvent such as water or alcohol, as its essential components.
Since such conventional resist removing agents cannot remove polymer completely, a pre-removal step for removing polymer is further necessary. Polymer is a material produced by reaction of components constituting the resist pattern, such as carbon (C), hydrogen (H), or oxygen (O), and plasma when plasma etching or reactive ion etching (RIE) is performed to etch the underlying layers using the resist pattern as a mask. Particularly, when a metal layer is formed under the resist pattern, an organometallic polymer is produced. If such a polymer or organometallic polymer is not removed, but remains in a contact hole or a via hole, contact resistance increases. Thus, before using the resist removing agent, a cleaning reinforcement agent capable of removing polymer, e.g., a nitric acid solution (HNO.sub.3), must be used to treat the substrate during a pre-removal step.
The conventional resist removing agent may attack the underlying layers. A typical example of an underlying layer liable to be attacked is a metal layer. The reason for the foregoing is because the resist removal agent is mainly comprised of a basic solvent or water which easily corrodes the metal layer. Thus, a post-removal step for preventing the attack must be further carried out before executing a post-removal rinse step. In the post-removal step, isopropyl alcohol (IPA) is used for example.
Therefore, since a nitric acid treatment step (i.e., a pre-removal step) and an isopropyl alcohol treatment step (i.e., a post-removal step) are further performed, the resist removal process becomes more complicated and processing time is prolonged, thereby lowering productivity. Also, since a pre-removal material, e.g., nitric acid and a post-removal material, e.g., isopropyl alcohol, are further required as well as the resist removal material, the manufacturing cost increases. In addition, since various baths for the pre-removal step and the post-removal step are required, a resist removing apparatus becomes unnecessarily bulky.